Engine starting and propeller blade pitch adjusting apparatus



May 6, 1952 1.. c. DERMOND ENGINE STARTING AND PROPELLER BLADE PITCH ADJUSTING APPARATUS Original Filed March 19, 1943 2 SHEETS-SHEET 1 May 6,1952 g/DERMQND ENGINE STARTING AND PRdPELLER BLADE PITCH ADJUSTING APPARATUS Original Filed March 19, 1943 2 SHEETS-SHEET 2 these being shown at 28.

Patented May 6, 1952 ENGINE STARTING AND PROPELLER BLADE PITCH ADJUSTING APPARATUS Lawrence C. Dermond, Anderson, Ind, assignor to General Motors Corporation, Detroit, Mich, a corporation of Delaware Continuation of application Serial No. 479,762,

March 19, 1943.

1944, Serial No. 526,702

8 Claims. 1

This invention relates to airplanes and it aims to provide mechanisms operated by the same electric motor for starting the engine of the airplane and for adjusting the pitch of its propeller blades.

This application is a continuation of Serial No. e79,762, filed March 19, 1943, now abandoned Further objects and advantages of the present invention Will be apparent from the following description, reference being had to the accompanying drawings wherein a preferred embodiment of the present invention is clearly shown.

In the drawings:

Fig. 1 is a longitudinal sectional view of an electric motor and mechanisms operated thereby for starting the engine, or changing the propeller blade pitch.

Fig. 1a a sectional View on line iala of Fig. 1.

Fig. 2 is a diagram showing the engine cranking or starting circuit and the engine running or propeller pitch adjusting circuit of the electric motor and showing other apparatus for maintaining a selected propeller blade pitch.

Figs. 3 and i are sectional views taken respectively on the lines 3-3 and 4-4 of Fig. 1.

Fig. 5 is a fragmentary sectional view taken on line 5-5 of Fig. 1.

Referring to Fig. 1, the frame of the engine supports a ball bearing 21 which supports a housing comprising members 22 and 23 secured by screws 24 shown in Fig. 3 which shows the housing member 23 separated from housing member 22. When fastened together the members 22 and 23 provide bearings for the shanks or roots 25 of propeller blades 25. The engine crank shaft 21 is rotatably supported by a number of bearings provided by the crank case 25, one of The shaft 2? drives the housing members 22 and 23 through the splines 23 provided by the shaft 2'! and the member 22. Member 22 is retained on shaft 27 by nut 30 engaging the threaded end of shaft 21.

Housing 23 provides the field frame of an electric motor M and supports pole pieces 3| surrounded by field windings 32 and an armature 33 which together with a commutator 34 is mounted on a shaft 35 rotatably supported by plates 35 and 31. Plate 36 has a flange 3B fitting within a bore 39 at the left end of housing 23. Plate 37 fits within a counter-bore in housing 23 providing a shoulder 45. Plates 36 and 31 are secured together by through bolts 4| and cooperating nuts 42. A nose shell 43 is secured to plate 36 in any suitable manner. commutator brushes not This application March 16,

2 shown are insulatingly supported by the plate 36.

Housing 23 supports a plate 45 received within a counter-bore forming a shoulder 45. Plate 55 is retained by a ring nut 41' and therefore retains a spacer sleeve 48, a ring gear 49 and a spacer sleeve 55. Plate 5 provides a bearing for a shaft 5: supported also by a bearing at 52 provided by crank shaft 27. Shaft 51 has a splined portion 53.

Motor armature shaft 35 drives a sun gear 55 meshing with planet gears 56 rotatably on studs 51 carried by planet gear spider 58. Gears 56 are retained on the studs 51 by washers 59 and pins 65. Planet gears 55 mesh with ring gear Spider 58 is d ivingly connected with shaft through squared portion 6! of shaft 5! which fits in a square hole in the hub of the spider 58.

Shaft 53 is connectible either with engine cranking gears or with propeller blade adjusting gears. For this purpose, the splines 53 of shaft 51 mesh with similar splines provided by a magnetizable armature 53 urged by a spring 64 toward the left so that clutch teeth 65 provided by armature G3 normally mesh with clutch grooves 65 of a bevel gear at having a bearing sleeve 68 journalled on shaft 5!. Gear 6'! meshes with bevel gears 59 respectively connected with propeller blade roots 25. V

Armature 53 is moved toward the right against the action of spring as by an electromagnet comprising a winding 1i) located in a magnetizable core it supported by arms 12 extending radially and fitting into grooves 13 provided by housing 23 (Fig. 3) and located by dowel pins 74. When magnet winding H3 is energized, armature 63 moves toward the right to disengage its teeth 55 from grooves 56 of gear ill and to cause its clutch teeth '55 to engage with clutch teeth 15 provided by a gear ll having a bearing sleeve 18 journalled on shaft 5 Gear ll meshes with gear 86 secured to a shaft 3i having a squared portion 82 extending through a square hole in a gear 83 meshing with a ring gear 35 supported by engine crank case 25 and retained by a ring nut 85. Endwise movement of shaft 8! is prevented by the crank case 20 at the right end of the shaft and by a washer 35 abutting the left side of gear and surrounding the hub of gear ll and retained by the spring 64.

When the shaft 35 of motor M rotates, the shaft 51 is driven at a reduced speed through the planetary gearing including sun gear 55 and planet gears ttwhich are'caused to roll within the ring gear 49 and thereby to drive the studs 51 and the plate 58. When shaft 51 is connected with gear 61 as shown, rotation of motor shaft 35 in either direction will change the pitch of the propeller blades 26. When it is desired to crank the engine, the magnet coil 10 and the motor M are connected with a current source in order that gear 51 will be disconnected from shaft 5I and that shaft 5| will be connected with gear 11. Gear 11 rotates to cause rotation of gear 80, shaft 8| and gear 83. Rotation of gear 83 causes it to roll within the ring gear 84 and thereby cause orbital motion of the shaft 8| thereby causing rotation of housing 22 and rotation of engine crank shaft 21.

From a control apparatus to be described with reference to Fig. 2, there extend four wires SI, 92, 93 and 94, housed in an insulating cable 90 and terminating in brushes Il, I02, I03, and I04, respectively, engaging, respectively, metal rings III, H2, H3 and II4 supported by nonconducting annular plate II attachedtohousing member 22. The rings III through H4 are connected respectively with wires I2I, I22, I23 and I24 as shown best in Fig. 2. Wire I2I leads to magnet coil connected with wire I24. Between wire I24 and motor brush I25 there are connected two parallel-connected magnetic brake release coils 200. Wires I22 and I23 are connected respectively with normally closed limit switches I99-l and I93r connected respectively with field windings I32 and I33 connected with motor brush I35. Fields I32 and I33 are so wound as to produce opposite rotations of the motor armature 33. Hence, only one of the field windings I32, I33 is used at a time, depending upon which direction the motor is required to rotate. The shaft 35 of the motor M is shown in Fig. 2 diagrammatically connected by gears a and b with the bevel gear 61. This is merely a diagrammatic representation of the mechanism shown in detail in Fig. l. The connections between the motor shaft and the crank shaft for engine starting purposes are not shown in Fig. 2.

When a controller handle I pivoted at MI is moved into the start position, a contact I42 bridges contacts I43, I44 and I45, thereby connecting a current source such as a battery I46 with rings III and H2, thereby connecting the source with electromagnet coil 10 and with the motor M, the field winding I32 being operative to cause the motor shaft 35 to rotate in a direction correct for engine cranking purposes.

Since the normal position of the parts is that shown in Fig. 1, the magnet 10 has to be energized to enable the starting motor to crank the engine. The energization of magnet coil 10, according to the circuit shown in Fig. 2, causes the attraction of armature 63, shown in Fig. 1, so as to disconnect gear 61 from the motor M and connect the motor with the gear 11 and other gears of the train of engine cranking gears. When the engine has been started, the handle I40 is moved into the run position, as shown, thereby causing a contact I41 to bridge contacts I48 and I49, thereby connecting the battery I46 with a plate I50 carrying contacts I5I and I52 adapted to engage contacts I53 and I54 respectively, which are connected with wires 92 and 93, respectively. The engagement of these contacts is controlled by speed responsive means which causes the motor M to adjust the propeller blade pitch so that a certain selected engine speed will be maintained.

The pitch control apparatus comprises a rod I attached to plate I50 and insulated therefrom. Rod IE0 is attached to a metal bellows I6I housed within a box I62 to which the upper end of the bellows I6I is attached. Between the lower end of the bellows and the bottom wall of the housing is located a spring I63 which is opposed by fluid pressure within the bellows I3I. The source of fluid pressure may be the engine oil system with which the control apparatus is connected by a pipe I54 having a branch 155 communicating with the interior of bellows i6I. Pipe I54 leads to a chamber I provided by a stationary box I51, supporting slide valves I08 and I69 having grooves I10 and HI, respectively, and communicating ports I12 and I13 respectively. Slide valve I68 is manually adjusted by an arm I14 for the purpose of selecting various engine speeds to be maintained. Slide valve I69 is adjusted by arms I15 integral with governor weights I10 pivoted at I11 upon brackets I18 provided by a weight base plate I19 driven by a shaft I80 having pilot surfaces I8I and I82 for guiding the slide valve I59. Shaft I80 carries a bevel gear I83 meshing with an engine driven bevel gear, not shown. As speed increases, the weights I16 tend to separate and this action is opposed by a spring I86 connected at its ends with stirrups I81 connected with the weights by adjustable screws I88. Shaft I80 is provided with a longitudinal passage I89 communicating with side passages I90 and I9I, thereby placing the space I92 in the slide valve I69 in communication with the low pressure oil return pipe of the engine oil system. Pipe I64 is connected with the high pressure oil supply. When pipe IE4 is bled to a predetermined extent as determined by the overlapping of port I12 of valve I68 with the groove I1I of valve I63, the pressure then existing in the bellows I1I will oppose the spring I63 to such extent that the two forces will be in equilibrium, the contacts I5I and I52 being separated from the contacts I53 and I54. In this status of the apparatus, the propeller pitch is being maintained at the desired angle for allowing the engine to maintain a certain speed. As the speed of the engine varies, the weights I16 will be brought together by the spring I86, thereby causing the slide valve I69 to move downwardly to stop the bleeding of pipe I64, whereupon pressure in the bellows I6I increases and contacts I52 and I54 are engaged, thereby causing the motor M to operate with the field winding I33 energized. This causes such rotation of the propeller blade roots 25 as to cause the pitch to decrease so that the engine speed will increase. On the other hand, if engine speed increases above the set speed, then the weights I10 will move apart and the valve I69 will move upwardly to increase the bleeding, thereby decreasing the pressure in bellows I6I and thereby allowing the spring I53 to elevate the contact I5I into engagement with contact I53. Then the motor operates with its field I52 energized and causes the propeller blade roots to be rotated so that the pitch will increase, thereby causing the engine speed to decrease. In this way engine speed is maintained within required limits of certain selected speed. The selected speed is varied by moving the slide valve I68. If valve is moved down, the governed speed of the engine will be decreased; and, if valve I58 is moved up, the governed speed of the engine will be increased. When the engine is not running or is not to be started, the controller handle I40 is moved to the offf' position, thereby disconnecting the battery I45 from the motor M and the magnet coil 10.

When the circuit between motor M and battery M6 is interrupted, its shaft 35 is held stationary by a brake comprising a drum 2M fixed to shaft 35 and engaged by shoes 202 pivoted upon studs 203 fixed to plate 36. Spring 204 urges the shoes 202 against the drum I. When the motor circuit is closed, coils 200 are energized and cause attraction of the shoes 202 toward the pole faces of magnetizable cores 205 which are surrounded by the coils 299 and which are carried by brackets 206 fixed to plate 36. Therefore, the required propeller pitch is maintained while the motor is not operating to change the pitch.

The extents to which the propeller pitch is changed in either direction to effect increase or decrease in speed are limited by the opening of the limit switches [Bil-Z or I901. These switches are opened when their spring blades l9 l-l or I911 are contacted and moved by a pin I92 carried by the gear 61 as shown in Fig. 5. The limit switches ISO-Z and l90r are insulatingly supported by plate 45 (Fig. l) in any suitable manner.

During cranking, the blades 26 are free to turn to the angle offering least resistance to the rotation of the engine.

While the embodiment of the present invention as herein disclosed, constitutes a preferred form, it is to be understood that other forms might be adopted, all coming within the scope of the claims which follow.

What is claimed is as follows:

1. Engine starting and propeller pitch changing apparatus comprising, an internal combustion engine, a propeller operated thereby and having blades supported for rotation about the axes of their roots, an electric motor, a. current source, two circuits respectively for causing the motor to be connected with the source for operation of the motor in opposite directions, a third circuit for causing the motor to be connected with the source for operation of the motor in a direction to crank the engine, means responsive to engine speed for controlling the first two circuits in order that the motor will rotate the blades to a pitch setting required to maintain a selected engine speed, means for modifying the operation of said control means in order to vary the governed speed of the engine, gearing for connecting the motor with the blades for pitch adjustment thereof, gearing for connecting the motor with the engine for cranking purposes, and means for selectively rendering operative the control of the motor through the first two circuits or for causing the motor to operate as a starting motor and concurrently therewith for disconnecting the first mentioned gearing and connect ing the second mentioned gearing.

2. In a power plant for aircraft the combination of an internal combustion engine, a variable pitch propeller, a current source, an electric motor operable by said current source, operating mechanism normally connecting the motor in driving relation with the propeller blades and effective to rotate such blades about their axes in order to change the pitch of the propeller upon operation of said motor, means for disabling said operating mechanism and for establishing a driving connection between said motor and the engine so that the same motor may be rendered operative to rotate the engine for starting purposes, an electromagnet for operating said last named means, a series of circuits for connecting the electromagnet and the motor with the current source, a manually operable controller for controlling the completion of said circuits in order to control the effectiveness of the electromagnet and motor,

said controller having two operative positions, in both of which the motor circuit is closed, but in one of which the magnet is energized whereby in one position of the controller the motor is caused to operate the engine and in the other the motor is connected with the propeller blades, and an automatic circuit controlling means operable by fluid pressure also effective to control the action of the motor when the manual controller is in such position as to bring about the connection of the motor with the propeller blades.

3. In a power plant for aircraft the combination of an internal combustion engine, a variable pitch propeller, a current source, an electric motor operable by said current source, operating mechanism normally connecting the motor in driving relation with the propeller blades and effective to rotate such blades about their axes in order to change the pitch of the propeller upon operation of said motor, means for disabling said operating mechanism and for establishing a driving connection between said motor and the engine so that the same motor may be rendered operative to rotate the engine for starting purposes, an electromagnet for operating said last named means, a series of circuits for connecting the electromagnet and the motor with the current source, a manually operable controller for controlling the completion of said circuits in order to control the effectiveness of the electromagnet and motor, said controller having two operative positions, in both of which the motor circuit is closed, but in one of which the magnet is energized whereby in one position of the controller the motor is caused to operate the engine and in the other the motor is connected with the propeller blades, and an automatic circuit controlling means operable in' response to engine speed also effective to control the action of the motor when the manual controller is in such position as to bring about the connection of the motor with the propeller blades.

, 4.. In a power plant for aircraft the combination of an internal combustion engine, a variable pitch propeller, a current source, an electric motor operable by said current source, operating mechanism normally connecting the motor in driving relation with the propeller blades and effective to rotate such blades about their axes in order to change the pitch of the propeller upon operation of said motor, means for disabling said operating mechanism and for establishing a driving connection between said motor and the engine so that the same motor may be rendered operative to rotate the engine for starting purposes, an electromagnet for operating said last named means, a series of circuits for connecting the electromagnet and the motor with the current source, a manually operable controller for controlling the completion of said circuits in order to control the efiectiveness of the electromagnet and motor, said controller having two operative positions, in both of which the motor circuit is closed, but in one of which the magnet is energized whereby in one position of the controller the motor is caused tooperate the engine and in the other the motor is connected with the propeller blades, and an automatic circuit controlling means operable in response to engine speed also effective to control the action of the motor and its direction of rotation when the manual controller is in such position as to bring about the connection of the motor with the propeller blades.

5. In a power plant for aircraft, the combination of an internal combustion engine, a variable pitch propeller operated thereby, means for variably moving the blades thereof to change the pitch of said blades during the operation of said propeller by the engine to thereby control the governed speed of said engine, means for automatically and variably controlling the pitch changing movement of said blades as desired to maintain operation of the engine at any selected speed, a current source, an electric motor operable by current from said source, operating connections between the motor and the engine and between the motor and said blade moving means whereby the motor may be operatively connected with the engine when the latter is inoperative in order to start it, or may be connected with the blade moving means during engine operation to effect pitch changing movements of the blades in order to control engine speed, control mechanism movable to different positions to determine whether the motor is operatively connected to the motor or to the blade moving means, and automatic fluid pressure means operable to determine the direction of rotation of the motor when said motor is connected to the blade moving means.

6. In a power plant for aircraft, the combination of an internal combustion engine, a variable pitch propeller operated thereby, means for variably moving the blades thereof to change the pitch of said blades during the operation of said propeller by the engine to thereby control the governed speed of said engine, means for automatically and variably controlling the pitch changing movement of said blades as desired to maintain operation of the engine at any selected speed, a current source, an electric motor operable by current from said source, operating connections between the motor and the engine and between the motor and said blade moving means whereby the motor may be operatively connected with the engine when the latter is inoperative in order to start it, or may be connected with the blade moving means during engine operation to effect pitch changing movements of the blades in order to control engine speed, control mechanism movable to different positions to determine whether the motor is operatively connected to the engine or to the blade moving means and automatic means responsive to engine speed for determining the direction of rotation of the motor when said motor is operatively connected to the blade moving mechanism.

7. In a power plant for aircraft, the combination of an internal combustion engine, a variable pitch propeller operated thereby, means for variably moving the blades thereof to change th pitch of said blades during the operation of said propeller by the engine to thereby control the governed speed of said engine, means for automatically and variably controlling the pitch changing movement of said blades as desired to maintain operation of the engine at any selected speed, a current source, an electric motor operable by current from said source, operating connections between the motor and the engine and between the motor and said blade moving means whereby the motor may be operatively connected with the engine when the latter is inoperative in order to start it, or may be connected with the blade moving means during engine operation to effect pitch changing movements of the blades in order to control engine speed and means responsive to engine speed for controlling the operation of said motor to effect pitch changing movement of the blades.

8. In a plant for aircraft, the combination of an internal combustion engine, a variable pitch propeller operated thereby, means for variably moving the blades thereof to change the pitch of said blades during the operation of said propeller by th engine to thereby control the governed speed of said engine, means for automatically and variably controlling the pitch changing movement of said blades as desired to maintain operation of the engine at any selected speed, a' current source, an electric motor operable by current from said source, operating connections between the motor and the engine and between the motor and said blade moving means whereby the motor may be operatively connected with the engine when the latter is inoperative in order to start it, or may be connected with the blade moving means during engine operation to effect pitch changing movements of the blades in order to control engine speed, control mechanism movable to different positions to determine whether the motor is operatively connected to the engine or to the blade moving means and means responsive to engine speed for controlling the operation of said motor to effect pitch changing movement of the blades.

LAWRENCE C. DERMOND.

REFERENCES CITED The following references are of record in the file of this patent:

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